Hi Tabbycat1
The answer is it’s best not to clean out of the hog box whilst the hog is still resident. (I include as ‘resident’ even if the hog is out at night). I know we like to think of them of them as houses which need to be cleaned out, but to the hog they are just a convenient structure within which they can nest, sleep, hibernate, etc. Normally hogs change nest sites from time to time and hopefully the hog will eventually move out and give you an opportunity to clean it out. Hogs being wild animals must be allowed to make their own choices. There is more information here: https://www.hedgehogstreet.org/cleaning-out-boxes/
But, they aren’t like pet cages when you must clean them out regularly. Other than hibernation, they are normally used just for sleeping and rearing young so that they would not normally poo, etc. in their nests – that would happen when they are out at night.
The only exception I might make to the above is if I have seen that the hog is heavily infested with ticks, etc. which might then re-infest the hog when they lay eggs in the box. In that case it might become more of a rescue situation. As said previously, a hog would normally change nests from time to time and avoid that happening, but it might happen on occcasions.
You might like to think about getting/making another hog house. Sometimes people place another one not too far away and the hog decides to move in there instead, giving you the opportunity to clean out the old house.
Good luck.
